Disease Directory

    Septoria Leaf Spot

    Septoria lycopersici, Septoria spp.

    Fungus
    Leaves

    Overview

    A common fungal disease of tomatoes and other plants, causing numerous small, circular spots with dark borders and tan to gray centers, often with tiny black fruiting bodies visible in the center.

    Symptoms

    Numerous small (1-3mm), circular spots with dark brown borders and grayish-white centers. Tiny black pycnidia (fruiting bodies) visible in spot centers with a hand lens. Lower leaves affected first, progressing upward. Severe defoliation.

    Environmental Conditions

    Humid

    Prevention

    Rotate crops on a 3-year cycle. Remove plant debris after harvest. Mulch to prevent soil splash. Stake plants for air circulation. Use disease-free transplants.

    Management

    Apply copper-based fungicides at first signs. Remove infected lower leaves. Improve air circulation. Avoid overhead watering. Chlorothalonil or mancozeb for severe outbreaks.